Manufacture of sodium 2, 4, 5-trichlorophenoxyacetate



produced by reaction of terials.

, the separation step,

pI-I ofthe reaction mixture to about 10 by; the 1 addition of caustic in order to avoid separation of a' product containing 2,4,5-trichlorophenoxycooled to precipitate additional product Water may be used as the reaction diluent be- 1 cause of the very low solubility of the sodium 1 2,4,5-trichlorophenoxy acetate.

eventually discharged from the process it is particularly' advantageous, however, to utilize as the 1 reaction diluent a brine solutioncontainings dium chloride in the approximate concentration the original starting ma-- Sodium 2,4,5-trichlorophenoxyacetate i is substantially insoluble in brine solution containing about 8 to 10 per cent or more of sodium 3 chloride based'on the salt and water presentin the mixture. 1 without significant loss, but I have found that 1 product loss can be still further reduced by employin'g'a brine reaction diluent which comprises 1 recycledseparated reaction liquor. l 7

Since water 7 is This material can be discarded of the reaction and before it is advisable to adjust the Upon completion- 1 aceticacid' in admixture with the sodium salt and 1 thus protect product quality and reduce losses to a minimum. The sodium salt product may be converted, for example, to the free acid which usually is the desired product by dissolvingthe sodium salt in water or per cent methan'ola'rid by -acidifying the solution with" a dilute acid such as sulfuric acid. The precipitated organic acid is removed by filtration or centrifugg, is washed andis dried. i v

. v ,M 11280 parts'of 2,4,5-trichlorophenol were dissolved in 1360Tparts of.19.1 percent aqueous caus- The solution'was heated under reflux for about 11.25 ;hours,.. and at that time was diluted with l4830"parts: of. S'percent aqueous salt'solution.

. 'The refiuxing was. continued for a totalitime of refiu'xingo'f' about 3 hours.

The crystals of 'sodium. 2,4,5-trichlorophenoxyacetate. which separated wierevery fibrous andeasily filtered. "Thecakewas washed with 8 percent salt solution and dried. The yield, based on the-chloroaceticacid used, was 75.3 percent. I

In an exactly comparable run except that the diluent brine was added initially to the reaction -mixture, a yield "oi-.'onlyw63.8 percent was' 'obtained..' A portion of the sodium 2 ,4g5-trichlorophenoxyacetate produced according to the first paragraph'of this example was dissolved in 50 percent methanol and acidified with dilute-sulfuric acid. -The' precipitated 2,4,5-trichlorophenoxyac'etic acid was filtered, washed and dried. I .It .was a product of high purity. v I

" Example II The procedure of Example I was followed, adding'the 8 percent brine as diluent afterthe reaction mixturehad refluxed'ior about 1 hour. .The total number ofmoles of water after dilu- 3 My invention will be further illustrated in the: V -following -illustrative.examples: L

4 r 7 tion was about 77 moles. The yield was 80.5 percent based on the chloroacetic acid and the product was 9'? percent sodium 2,4,5-trichlorophenoxyacetate.

. ample III The p v u mple was repeated except that water instead of brine was used as the diluent; A yield of 72.3 percent was obtained and the product contained about 93.5 percent of sodium 2,4,5-trichlorophenoxyacetate.

chloroacetic acid was 41.6 to 1 before dilution and 74 to 1 after dilution with water. The reaction mixture after refluxing was filtered hot and the cold filtrate refiltered. The combined solids when washed and dried represented a yield of 82.8 per cent.

Thus my invention provides a method 'for -manufacturing "sodium 2,4,5-trichlorophenoxyacetate of improved convenience and greatly reduced cost in terms of product handling. In addition the product of my invention is more 'floc'culent and therefore iseasier to handle in subsequent operations than the conventional baked product. Compared to proposed aqueous systems analogous to those used in sodium 2,4 dichlorophenoxyacetate production, my in-' vention provides-economies in equipment size and 'processcapacity improved yields and higher reaction rates which reduce the time of react ion significantly.

I claim: 1

1. In the manufacture of sodium 2,4,5-trichlorophenoxyacetate by condensation of 2,4,5-trichlorophenol and .chloroacetic acid in alkaline solution, the improvement which comprises forming an'aqueous mixture containing sodium 2,4,5-trichlorophenate and sodium chloroacetate in approximately stoichiometric proportions and which contains from about 19 to about 50 moles of water to '1 mole of the sodium chloroacetate,

(reacting the mixture at elevated temperature for about 3 hours, maintainingxthemixture in liquid slurry 'form by. adding water during the course of the reaction in an amount at least sufficient to bring the total quantity of :water usedin the process to. about 74' moles'to 1 mole -of sodium chloroa'cetate' and recovering the solid product by separation: from the. reaction mixture 2 .j' .2 .i I 2. In the manufacture of sodium, 2,4,5-t'richlorophenoxyacetate by condensation of 2,4,5-tri- "chlorophenol and chloroacetic acid in alkaline solution, the improvement. which 'comprises forming an aqueous mixture containing sodium 2,4,5 -trichlorophenate and sodium; chloroacetate in approximately stoichion'letric proportions and 'which contains about 30' to 45 moles or water to 1 mole ofthe sodium chloroacetate, reacting the mixturebat elevated temperature for about 3 hours, maintaining themixture' in' liquid'slurry form by adding water during the course of the reaction in an amount at leastsuficientto bringthe total quantity of water used in: the process to about 74moles'to 1. mole of sodium chloroacetate and recoveringthesolid product by separation from thereaction mixture.

3. The method: of claim 2 in which'the dilutioni iseffected'with brine contain'ngabout 8 to 10 per cent sodium chloride. l

c Number 2,598,692 5 4. The method of claim 2 in which the dilution water comprises separated reaction liquor.

GUSTAV J. HENRICH. Number REFERENCES CITED 5 573,479

The following references are ot -record in the file of this patent: 9 2

UNITED STATES PATENTS Name Date 2,516,611 Berhenke et a1. July 25) 1950 (1941).

6 FOREIGN PATENTS Country Date Great Britain Nov. 22, 1945 Great Britain .."Nov. 22, 1945 Great-Britain Nov. 23, 1945 Great Britain Sept. 30, 1947 OTHER REFERENCES Pokorny, J. Am. Chem. Soc.. vol. 63, p. 1768 

1. IN TH EMANUFACTURE OF SODIUM 2,4,5-TRICHLOROPHENOXYACETATE BY CONDENSATION OF 2,4,5-TRICHLOROPHENOL AND CHLOROACETIC ACID IN ALKALINE SOLUTION, THE IMPROVEMENT WHICH COMPRISES FORMING AN AQUEOUS MIXTURE CONTAINING SODIUM 2,4,5-TRICHLORPHENATE AND SODIUM CHLOROACETATE IN APPROXIMATELY STOICHIOMETRIC PROPORTIONS AND WHICH CONTAINS FROM ABOUT
 1. TO ABOUT 50 MOLES OF WATER TO 1 MOLE OF THE SODIUM CHLOROACETATE, REACTING THE MIXTURE AT ELEVATED TEMPERATURE FOR ABOUT 3 HOURS, MAINTAINING THE MIXTURE IN LIQUID SLURRY FORM BY ADDING WATER DURING THE COURSE OF THE REACTION IN AN AMOUNT AT LEAST SUFFICIENT TO BRING THE TOTAL QUANTITY OF WATER USED IN THE PROCESS TO ABOUT 74 MOLES TO 1 MOLE OF SODIUM CHLOROACETATE AND RECOVERING THE SOLID PRODUCT BY SEPARATION FROM THE REACTION MIXTURE. 